Study Tests Theory About Prolotherapy Injections for Knee Pain
Ligament and tendon injuries—sprains and strains—are common, accounting for more than 5 million visits to hospital emergency departments in the United States each year. Often these injuries don't heal completely, and the result can be chronic pain, joint problems, and increased risk for osteoarthritis. Because people may not respond to standard treatments such as rest, nonsteroidal anti-inflammatory drugs (NSAIDs), and corticosteorid injections, prolotherapy is becoming increasingly popular as an alternative treatment.
Prolotherapy involves injections of “proliferant” solutions at the pain site. The proliferants are thought to strengthen and “reorganize” injured tissue and decrease pain by creating an irritation that alters the inflammatory process. In an NCCAM-funded study, researchers at the University of Wisconsin investigated whether the three most commonly used proliferants—D-glucose (dextrose), phenol-glucose-glycerine (P2G), and sodium morrhuate—cause an inflammatory response in knee ligaments. They injected the substances into the knees of laboratory rats and examined the tissue after 6, 24, and 72 hours. They also examined tissue from animals in three control groups: no injection, needlesticks, and saline injection.
Compared to no-injection controls, prolotherapy injections produced an inflammatory response, but the response was about the same as that for the needlestick and saline-injection controls. The researchers conclude that the proliferants themselves may not be responsible for the inflammatory effect. They suggest that future studies of prolotherapy in animals and people control for the effects of the injection itself.
Jensen KT, Rabago DP, Best TM, et al. Early inflammatory response of knee ligaments to prolotherapy in a rat model. Journal of Orthopaedic Research.; 26(6):816–823.2008